Background : The bare area, which lies between the right liver and diaphragm, should be dissected to mobilize the right liver. The bare area was reportedly formed by direct adhesion between the liver and diaphragm, meaning that the bare area lacked serosal components. This study aimed to analyze the structure of the bare area by an integrated study of surgical and laparoscopic images and pathological studies and describe surgical procedures focusing on the multilayered structure.
Methods : Surgical specimens of hepatectomy were analyzed histologically to evaluate the macroscopic structure of the bare area. Laparoscopic images and cadaver anatomy of the bare area were also examined, changing the dissection layers of the bare area.
Results : The bare area comprised a multilayered structure that resulted in fusions in the hepatic development among the parietal peritoneum (peritoneum of the diaphragm part) and the visceral peritoneum (liver serosa). The multilayered structure of the bare area comprised the liver, sub-serosal connective tissue, liver serosa, parietal peritoneum, retroperitoneal connective tissue, epimysium of the diaphragm, and diaphragm, in order from the liver to the diaphragm. Laparoscopic images sometimes enabled us to recognize the multilayered structure of the bare area.
Conclusions : Histopathological findings showed the bare area to be a multilayered structure. In cases where tumors are located underneath the bare area, it could be important to dissect the bare area, with careful attention to its multilayered structure. Surgical dissection of the bare area in the outer layer of the fused peritoneum could allow a sufficient safety margin.